Heat exchange coil



Jain. 10, 1939. 2,143,287

HEAT EXCHANGE COIL Filed Feb. 29, 1936 Patented Jan. 10, 1939 UNITED STATES PATENT OFFICE 8 Claims.

This invention relates to a heat exchange coil, and the object of my invention is to provide an improved heat exchange coil which permits of free and rapid circulation of liquid within the coil and presents the greatest area of contact to the hot gases, and which may be placed in the combustion chamber of a furnace or in the fiue to utilize the waste heat in the flue gases. In furnaces, particularly those utilizing a blower for forced draught, burning either coal or oil, much heat is forced up the chimney which the ordinary type of heating coil is not able to extract. My invention makes possible the extraction of much of this waste heat to heat water either for domestic purposes or to supplement the main heating system.

The objects of this invention havebeen attained by constructing headers adapted to be positioned substantially horizontally and arranged one above the other in a vertical plane with vertical helical coils connecting the lower and upper headers. The headers are preferably formed from the arms of a U-shaped tube. The vertical helical coils are arranged in pairs. In each pair the inner coil is wound in the opposite direction to, and staggered with the outer coil thus presenting the maximum area of the coils to the hot flue gases passing through and around them. The ends of the coils are connected to the sides of the headers at points spaced apart throughout the length of the arms or headers.

The invention is hereinafter more particularly described and is illustrated in the annexed drawing in which Fig, 1 is a, side elevation partly broken away of the heat exchange coil mounted in a furnace pipe.

Fig. 2 a plan view, partly broken away, of the heat exchange coil mounted in the furnace pipe.

Fig. 3 an end elevation of the heat exchange coil mounted in a furnace pipe; and

Fig. 4 a fragmentary side elevation of a coil adapted to be used in the combustion chamber of a furnace.

In the drawing like numerals of reference indicate corresponding parts in the different figures.

In a furnace pipe or flue l is mounted a U- shaped tube 2 with its arms horizontal and arranged one above the other, said arms forming, in effect, tubular headers. The ends 3 and 4 of the tube 2 are bent outwardly through the pipe l and may be soldered or brazed to the pipe where they pass through it. Tubes in the form of vertical helical coils 5, 6 and l extend between the upper and lower parts or arms of the U-shaped tube. Within said vertical helical coils 5, 6 and l. are three tubes in the form of smaller vertical helical coils 8, 9 and I0 wound in the opposite direction and so arranged that the turns of said inner vertical helical coils are staggered with the turns of the outer vertical helical coils. The coils are arranged so that their axes intersect the axes of the headers substantially at right angles.

The ends of the outer and inner coils are connected to the sides of the upper and lower parts of said Ushaped tube, all the coil connections being positioned on the same side of the apparatus at points spaced substantially equal distances apart. Spacing of the point of connection of each inner coil from the point of connection of each. outer coil is made possible by having the inner coils run in the opposite directions to the outer coils. The term side is usedto distinguish from the top and bottom of the upper and lower parts of the U-shaped tube when the tube is arranged with its arms substantially horizontal and the axes of the helical coils substantially perpendicular.

It will be observed that the ends of the coils extend inwardly towards the sides of the headers in substantially the direction and angle of pitch to. their point of connection with the headers.

The ends 3 and 4 of the U-shaped tube 2 may be connected to a hot water tank or to the main heating system,

The coil may be mounted in the combustion chamber of a furnace with the ends of the U- shaped coil 2 extending through the side wall, door, or door frame. In Fig. 4 I show the lower arm of the U-shaped tube 2 offset to bring the parallel ends closer together. This construction is adapted for installation in the combustion chamber of a'furnace where it is to be installed through a door of less height than width and where the ends of the tube 2 are to extend through the door or the frame thereof. The coil may be inserted through the door sidewise and arranged with helical coils in Vertical position in the combustion chamber. In this way a coil of much larger capacity than would otherwise be possible may be utilized without any change in the combustion chamber or furnace.

Preferably the upper arm of the U-shaped tube when installed slopes slightly upward from the bend to the outlet 3 to prevent gases or steam from being trapped, and for this purpose the arms of the U-shaped tube may be slightly divergent.

The said U-shaped tube and the vertical helical coils are made of a suitable material preferably copper, and may be connected by soldering or brazing.

Although my heat exchange coil.has been described in connection with a fiue pipe and the combustion chamber of a furnace for heating water, it may be used in other ways for heating or cooling other liquids or fluids.

What I claim as my invention is:

1. The combination of a flue pipe, and a heat exchange coil comprising a U-shaped tube with its arms substantially horizontal and arranged one above the other in a vertical plane, and a plurality of vertical coils extending between the arms of the U-shaped tube, the ends of the arms of the U-shaped tube being bent outwardly through the flue pipe and adapted to be connected to a tank or boiler.

2. A heat exchange coil comprising substantially parallel tubular headers and a plurality of coils extending between the headers and connected to said headers at longitudinally spaced points, the end of one of the headers being offset toward the other adjacent the end.

3. A heat exchange coil comprising a U-shaped tube and a plurality of pairs of helical coils extending between the arms of said U-shaped tube, one of each pair of coils being wound within the other, the coils being connected to said arms of the U-shaped tube at points substantially equal distances apart throughout the length of said arms, the inner coil of each pair being oppositely wound and staggered with respect to. the outer coil.

4. Heat exchange apparatus, comprising substantially parallel tubular headers having their axes spaced apart; a helical coil extending between and communicating with the headers, the axis of which intersects the axes of the headers substantially at right angles, the ends of the coil extending inwardly towards and being connected to the sides of the headers; and a second coil of reverse pitch positioned within the first mentioned coil and having its ends connected to the same sides of the headers as the ends of the first coil and in spaced relation thereto,

5. Heat exchange apparatus, comprising substantially parallel tubular headers having their axes spaced apart; a plurality of pairs of helical coils extending between the said headers, one of each pair of coils being wound within the other, the coils being connected to said headers at points substantially equal distances apart throughout the length of said headers, the inner coil of each pair being oppositely wound and staggered with respect to the outer coil.

6. Heat exchange apparatus, comprising substantially parallel tubular headers having their axes spaced apart; a plurality of pairs of helical coils extending between the said headers, one of each pair of coils being wound within the other, the coils being connected to said headers at points substantially equal distances apart throughout the length of said headers, the inner coil of each pair being oppositely wound with respect to the outer coil.

7. Heat exchange apparatus, comprising substantially parallel tubular headers having their axes spaced apart; a helical coil extending between and communicating with the headers, the axis of which intersects the axes of the headers substantially at right angles, the ends of the coil extending inwardly towards and being connected to the sides of the headers; and a second coil of reverse pitch positioned within the first mentioned coil and having its ends connected to the. sides of the headers at points spaced longitudinally of the headers from the points of connection of the corresponding end of the first coil.

8. Heat exchange apparatus, comprising substantially parallel tubular headers having their axes spaced apart; a helical coil extending between and communicating with the headers, the

axis of which intersects the axes of the headers substantially at right angles, the ends of the coil extending inwardly towards and being connected to the sides of the headers; and a second coil of reverse pitch positioned within the first mentioned coil and having its ends connected to the same sides of the headers as the ends of the first coil and in spaced relation thereto, the windings of said outer and inner coils being in staggered relationship.

EARL B. SMITH. 

